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A test series using 12 unembalmed cadavers was conducted to investigate factors affecting the creation of cervical spine damage due to impact to the top of the head. The test subjects were instrumented to measure head, T8 thoracic spine, and sternum acceleration responses. Photographic targets on the head and torso allowed analysis of impact motions from high-speed movies. The stationary test subject was struck by a guided, moving impactor mass of 56 Kg at 4.6-5.6 m/s. The impactor striking surface consisted of a biaxial load cell with padding to vary the contact force-time characteristics of the head/impactor. The orientation of the head, cervical spine, and torso was adjusted relative to the impactor axis to investigate the effect of spinal configurations on the damage patterns. Load and acceleration data are presented as functions of time and as functions of frequency in the form of mechanical impedance.

This study Investigates the response of human cadavers1, and live anesthetized and post-mortem primates and canines2, to blunt lateral thoraco-abdominal impact. There were 12 primates: 5 post-mortem and 7 live anesthetized; 10 canines; 1 post-mortem and 9 live anesthetized; and 3 human cadavers. A 10 kg free-flying mass was used to administer the impact in the right to left direction. To produce the varying degrees of injury, factors including velocity, padding of the impactor surface, location of impact site, and impactor excursion were adjusted. The injuries were evaluated by gross autopsy, and in the case of live subjects, current clinical methods such as sequential peritoneal lavage and biochemical assays were also employed. Mechanical measurements included force time history, intraortic pressure, and high-speed cineradiography to define gross organ motion.

Blunt abdominal trauma is a major cause of death in the United States. However, little experimental work has been done to clarify the mechanism of blunt abdominal injury and to quantify tolerance parameters for the abdominal organs. This paper describes a joint study by the Highway Safety Research Institute and the Section of General Surgery of The University of Michigan in which direct impacts were applied to livers and kidneys. The tests were performed in a high-speed testing machine at a controlled ram velocity and stroke limit. The organ was surgically mobilized in anesthesized Rhesus monkeys and then placed on a load cell while still being perfused in the living animal. Tests were performed at ram speeds of 120, 6000, and 12000 in/min (5, 250,and 500 cm/s). The resulting load-deflection data were normalized and average stress-strain curves plotted for each test. In addition, the resulting injury severity was estimated immediately after impact using an injury scale of 1 to 5.

This paper discusses the problem of occupant protection in severe rear-end collisions from the standpoint of high performance seat structures and head restraints. Consideration is given to both fixed head restraints and to deployable head restraints. Two-dimensional computer simulations of occupant kinematics in a variety of rear-end collisions are utilized to provide initial performance criteria for head restraint design configurations. The resulting prototype system underwent a test and development program on an impact sled. The results of the various prototype performances and general criteria for high performance head restraint systems are discussed.

The mechanics of skull fracture in humans has been investigated by many people for over 90 years. A variety of techniques has been used in past studies. Test specimens have been whole cadavers, cadaver heads, skulls and sections of skulls with material conditions including both fresh and embalmed tissue, both dried and moist. Test techniques have incorporated cadaver drop tests, drop towers, and universal testing machines with the impacting surfaces including large surfaces, both flat and curved, and localized flat and curved surfaces. Some of the studies used impact energy as the measured test parameter, others used impact load and some studies used both quantities to describe the impact. The results of recent studies on the mechanical properties of cranial bone suggest that local values of strain energy density present in the bone of an impacted skull may be the critical parameter in the initiation of skull fracture.

This paper presents the anatomical considerations and general principles of occupant restraint in the car crash environment with emphasis on the protection of the child auto occupant. Design criteria and typical performance problem areas in child restraint systems are discussed.

Two child restraint system sled tests with a child cadaver* and a 3-year old child dummy have been carried out at the Highway Safety Research Institute of The University of Michigan. Some differences between the kinematical response of dummy and cadaver were found. Two mathematical models have been formulated, using the MADYMO program package, for the special purpose of evaluating child restraint performance. A description of the validated dummy and cadaver model is presented together with a comparison of experimental and model results. A sensitivity study was conducted to have a better insight into the effects of various parameters on the child's response. To show the use of the model as a design tool, a simulation with an energy absorbing backstrap is presented. It is concluded that the mathematical model is a better simulation for the cadaver kinematics than the dummy.

In that the neck has a wide range of movements--flexion, extension, lateral bending and rotation, there is a large variety of types of neck fractures and fracture-dislocations. This paper describes these various fractures and dislocations emphasizing the mechanisms as determined from clinical experience and potential, neurological damage. Fractures and fracture-dislocations with and without spinal cord involvement have been extensively described in the medical literature. This paper will give a brief overview of some of the types of fractures, as well as the mechanisms involved in these injuries. For more detailed descriptions, the reader is encouraged to review the articles in the list of suggested readings found in this symposium proceedings.

The specification of information and specific data on the biomechanical quantities which describe the injury processes produced in the human neck are, at best, minimal. This paper discusses the problems associated with the topic and lists the quantitative information that does exist on the human neck injury tolerance.

Selected side-impact cases from the National Crash Severity Study (NCSS) were studied to determine similarities and differences between actual crashes and laboratory (sled) crash tests. Sled tests simulating side impact have been conducted almost exclusively at a 90° impact angle, so the NCSS cases analyzed were those with a near-side occupant and a reported 3 o'clock or 9 o'clock impact vector. Of the 91 cases studied, 51 were judged comparable to the laboratory situation. The remainder generally involved cars struck at a point remote from the passenger compartment, and often involved considerable rotation of the vehicle. Injuries for the 51 cases were tabulated by crash severity (Delta V) and were judged to be quite similar to those observed in laboratory (sled) tests at a slightly higher Delta V. Brief notes are appended concerning each of the reviewed cases.

Present head restraint systems quite often restrict rearward visibility, and when not properly adjusted, their effectiveness suffers. The deployable head restraint can overcome both these problems and in addition provide head restraint performance better than fixed systems. This paper describes a project to study the feasibility of deployable head restraints. Starting with two-dimensional computer simulations of front seat occupant kinematics in rear-end collisions, initial performance criteria for deployment times, and restraint configurations were determined for various impact velocities. Based on these criteria, two types of deployable systems were designed and constructed, one an inflatable system and the other a rigid sliding system. These prototype systems then underwent a test and development program using anthropomorphic dummies and an impact sled. The test program evaluated the effectiveness of the head restraint systems under high- and low-speed crash simulations.

A variety of mechanical head forms is used today in the evaluation of the crashworthiness of automotive interiors and the effectiveness of helmet designs. Most head forms are of a very rigid metallic construction, although frangible head forms that indicate skull fracture are presently available. None of the existing head forms can be considered a complete mechanical analog to the human head in terms of mechanical response. This paper describes the initial phases of the development of such a head form. The first step in the development of the model was the determination of the pertinent mechanical properties of the tissues of the human head (scalp, skull bone, dura mater, and brain). A testing program which determined these properties at both static and dynamic strain rates is described and the results are summarized. The second phase of the program was to find and develop synthetic materials which duplicated the mechanical properties of the human tissues.

Although child restraints are an increasingly common fixture in family cars, and even seatbelts are finding their way around children, both types of restraining systems are frequently not being used to their best advantage. Current restraint designs, misused in common ways, were studied using a variety of dummies under FMVSS-213 impact test conditions. Configurations addressed in this series include improperly installed child restraints', misused infant restraints, multiple children in too few belts, and a misused booster. Kinematic data from high-speed films are presented as well as appropriate load and acceleration data. Assessments of injury potential are made based on accepted criteria in combination with extensive laboratory testing and accident investigation experience. Results show that certain misuse configurations can have serious consequences for child occupants, while other variations from commonly accepted restraint practice perform reasonably well.

A series of head impacts were conducted with 15 unembalmed cadavers. The purpose of the tests was to study the application of three-dimensional motion analysis using accelerometry, brain vascular system pressurization and high speed cineradiography to the understanding of head injury mechanics. The implementation of the techniques is described and their effectiveness is discussed. The three-dimensional accelerometry technique using nine accelerometers was found to be applicable in direct head impacts. Analysis of the head acceleration data indicates the existence of brain motions which are independent of the motion of the skull. These motions were confirmed by the high speed cineradiographic films. Brain vascular system pressurization and time after death were found to play a role in determining the extent of the brain motions and the resulting brain injuries.

This paper presents the concepts and first group of test results from a project designed to: 1. Quantify thoracic impact response using cadaver and baboon subjects;* 2. Compile analytical functions relating thoracic kinematic response to injuries observed in the experiments; and, 3. Define performance specifications insuring response fidelity between human and surrogate thoraxes. The experiments, which vary G-level, velocity, and direction of impact, utilize restraint systems including belts, airbags, and EA-columns. Resulting injuries are recorded at autopsy and an AIS rating assigned. Using the kinematic accelerometer data, injury-predictive functions are generated using statistical regression procedures. The utilization of project results in developing performance specifications for surrogate thoraxes is discussed in conclusion.

This paper summarizes the rationale used to specify the geometric, inertial and impact response requirements for a small adult female dummy and a large adult male dummy with impact biofidelity and measurement capacity comparable to the Hybrid III dummy, the most advanced midsize adult male dummy. Body segment lengths and weights for these two dummies were based on the latest anthropometry studies for the extremes of the U.S.A. adult population. Other characteristic body segment dimensions were calculated from geometric and mass scaling relationships that assured that each body segment had the same mass density as the corresponding body segment of the Hybrid III dummy. The biomechanical impact response requirements for the head, neck, chest and knee of the Hybrid III dummy were scaled to give corresponding biomechanical impact response requirements for each dummy.

Direct impact to the larynx is usually prevented in accidents by the protective nature of the chin. In some situations, the occupant motions leave the larynx unprotected and susceptible to impact by the steering wheel rim or instrument panel. As one of the unpaired vital organs of the body, there is no easy way to provide an alternative for its functions when the larynx is lost or damaged. Information available on the tolerance of the unembalmed human larynx to force is quite limited. This paper describes a multidisciplinary study to determine the response of unembalmed human larynges to blunt mechanical loading and to interpret the response with respect to clinical data. Fresh intact larynges were obtained at autopsy and tested at either static or dynamic loading conditions utilizing special test fixtures in materials-testing machines. Load and deformation data were obtained up to levels sufficient to produce significant fractures in both the thyroid and cricoid cartilages.

The purpose of this paper is to describe a combination of state-of-the-art detailed accident investigation procedures, computerized vehicle crash and occupant modeling, and biomechanical analysis of human injury causation into a method for obtaining enhanced biomechanical data from car crashes. Four accident cases, out of eighteen investigated, were selected for detailed reconstruction. Three were frontal impacts while the fourth was lateral. The CRASH II and MVMA 2-D analytical models were used in the reconstruction process. Occupant motions, force interactions with vehicle components, accelerations on the various body segments, and much other information was produced in the simulation process and is reported in this paper along with scene and injury data from the accidents.